未找到主类Java程序

Question

我以为我在这个程序中添加了我的主代码，但它没有识别出来。我错过了吗？我得到错误paint.Paintbrush类在PaintBrush项目中找不到。我不知道在哪里可以包含主类，而不会返回错误。感谢您提供任何建议或帮助。

package PaintBrush;

import java.applet.Applet;
import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.Label;
import java.awt.Panel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;

/**
 *
 * @author Olive
 */
import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;

public class Paintbrush extends Applet implements MouseListener,
                                                  MouseMotionListener,
                                                  ActionListener
{
   // component declarations
   Button blackButton;
   Button redButton;
   Button greenButton;
   Button blueButton;
   Button penButton;
   Button lineButton;
   Button eraserButton;
   Button clearButton;
   Button squareButton;
   Button ovalButton;
   Button fillSquareButton;
   Button fillOvalButton;
   Label colourTitle;
   Label colourDisplay;
   Label toolTitle;
   Label toolDisplay;

   // required variables to store settings
   Color currentColour;
   int toolType;

   // variables to store interim coordinates
   int oldX = -1;
   int oldY = -1;

   public void init()
   {
      // create all the buttons
      blackButton = new Button("Black");
      redButton = new Button("Red");
      greenButton = new Button("Green");
      blueButton = new Button("Blue");
      penButton = new Button("Pen");
      lineButton = new Button("Line");
      eraserButton = new Button("Eraser");
      clearButton = new Button("Clear");
      squareButton = new Button("Square");
      ovalButton = new Button("Oval");
      fillSquareButton = new Button("F Square");
      fillOvalButton = new Button("F Oval");

      // add action listners for all the buttons
      blackButton.addActionListener(this);
      redButton.addActionListener(this);
      greenButton.addActionListener(this);
      blueButton.addActionListener(this);
      penButton.addActionListener(this);
      lineButton.addActionListener(this);
      eraserButton.addActionListener(this);
      clearButton.addActionListener(this);
      squareButton.addActionListener(this);
      ovalButton.addActionListener(this);
      fillSquareButton.addActionListener(this);
      fillOvalButton.addActionListener(this);

      // create the button bar panel
      Panel buttonPanel = new Panel();
      buttonPanel.setLayout(new GridLayout(6, 2));
      buttonPanel.add(blackButton);
      buttonPanel.add(redButton);
      buttonPanel.add(greenButton);
      buttonPanel.add(blueButton);
      buttonPanel.add(penButton);
      buttonPanel.add(lineButton);
      buttonPanel.add(eraserButton);
      buttonPanel.add(clearButton);
      buttonPanel.add(squareButton);
      buttonPanel.add(ovalButton);
      buttonPanel.add(fillSquareButton);
      buttonPanel.add(fillOvalButton);

      // create the status bar panel
      colourTitle = new Label("Colour: ");
      currentColour = Color.black;
      colourDisplay = new Label("Black");
      toolTitle = new Label("   Selected Tool: ");
      toolType = 0;
      toolDisplay = new Label("Pen (Scribble)");
      Panel statusPanel = new Panel();
      statusPanel.setLayout(new FlowLayout(FlowLayout.CENTER));
      statusPanel.add(colourTitle);
      statusPanel.add(colourDisplay);
      statusPanel.add(toolTitle);
      statusPanel.add(toolDisplay);

      // arrange final panels in a border layout
      this.setLayout(new BorderLayout());
      this.add(buttonPanel, BorderLayout.WEST);
      this.add(statusPanel, BorderLayout.NORTH);

      // add mouse listners to applet
      this.addMouseListener(this);
      this.addMouseMotionListener(this);
   }

   // event handling for when an action occurs (in this case, whenever
   // a button is pressed)
   public void actionPerformed(ActionEvent e)
   {
      // get the local graphics page to draw on
      Graphics page = this.getGraphics();

      // red button pressed: set the current colour to red
      // and update the status display
      if (e.getSource().equals(redButton))
      {
         currentColour = Color.red;
         colourDisplay.setText("Red");
      }

      // blue button pressed: set the current colour to blue
      // and update the status display
      if (e.getSource().equals(blueButton))
      {
         currentColour = Color.blue;
         colourDisplay.setText("Blue");
      }

      // green button pressed: set the current colour to green
      // and update the status display
     if (e.getSource().equals(greenButton))
      {
         currentColour = Color.green;
         colourDisplay.setText("Green");
      }

      // black button pressed: set the current colour to black
      // and update the status display
      if (e.getSource().equals(blackButton))
      {
         currentColour = Color.black;
         colourDisplay.setText("Black");
      }

      // pen button pressed: set the selected tool to '0'
      // and update the status display
      if (e.getSource().equals(penButton))
      {
         toolType = 0;
         toolDisplay.setText("Pen (Scribble)");
      }

      // eraser button pressed: set the selected tool to '1'
      // and update the status display
      if (e.getSource().equals(eraserButton))
      {
         toolType = 1;
         toolDisplay.setText("Eraser");
      }

      // square button pressed: set the selected tool to '2'
      // and update the status display
      if (e.getSource().equals(squareButton))
      {
         toolType = 2;
         toolDisplay.setText("Square");
      }

      // oval button pressed: set the selected tool to '3'
      // and update the status display
      if (e.getSource().equals(ovalButton))
      {
         toolType = 3;
         toolDisplay.setText("Oval");
      }

      // filled square button pressed: set the selected tool to '4'
      // and update the status display
      if (e.getSource().equals(fillSquareButton))
      {
         toolType = 4;
         toolDisplay.setText("Filled Square");
      }

      // filled oval button pressed: set the selected tool to '5'
      // and update the status display
      if (e.getSource().equals(fillOvalButton))
      {
         toolType = 5;
         toolDisplay.setText("Filled Oval");
      }

      // clear button pressed: get the size of the applet and draw
      // a clearing rectangle over it, to clear the screen
      if (e.getSource().equals(clearButton))
      {
         Dimension size = this.getSize();
         page.clearRect(0, 0, size.width, size.height);
      }

      // line button pressed: set the selected tool to '6'
      // and update the status display
      if (e.getSource().equals(lineButton))
      {
         toolType = 6;
         toolDisplay.setText("Line");
      }
   }

   // event handling for when the mouse button is first pressed
   public void mousePressed(MouseEvent e)
   {
      // store the coordinates for future reference
      oldX = e.getX();
      oldY = e.getY();
   }

   // event handling for when the mouse is dragged with the button
   // held down
   public void mouseDragged(MouseEvent e)
   {
      Graphics page = this.getGraphics();

      // scribble tool: draw a line from the old coordinates to the
      // new ones
      if (toolType == 0)
      {
         page.setColor(currentColour);
         page.drawLine(oldX, oldY, e.getX(), e.getY());

         oldX = e.getX();
         oldY = e.getY();
      }

      // eraser tool: clear a small rectangles' worth at the specified
      // coordinate
      if (toolType == 1)
      {
         page.clearRect(e.getX(), e.getY(), 10, 10);
         page.setColor(currentColour);
      }
   }

   // resolve method: used to swap two numbers around so the
   // smaller is always in element 0, and the larger in element
   // 1, of the returned array
   public int[] resolve(int newC, int oldC)
   {
      int start, end;

      if (newC < oldC)
      {
         start = newC;
         end = oldC;
      }
      else
      {
         start = oldC;
         end = newC;
      }

      int[] blah = {start, end};
      return blah;
   }

   // event handling for when the mouse button is released  
   public void mouseReleased(MouseEvent e)
   {
      // get the applet's Graphics page
      Graphics page = this.getGraphics();

      // resolve the coordinates so that the smaller of the x and y
      // coordinates can be picked out easily
      int newX = e.getX();
      int newY = e.getY();
      int[] x = resolve(newX, oldX);
      int[] y = resolve(newY, oldY);

      // tool type 2: draw a rectangle
      if (toolType == 2)
      {
         page.setColor(currentColour);
         page.drawRect(x[0], y[0], (x[1] - x[0]), (y[1] - y[0]));
      }

      // tool type 3: draw an oval
      if (toolType == 3)
      {
         page.setColor(currentColour);
         page.drawOval(x[0], y[0], (x[1] - x[0]), (y[1] - y[0]));
      }

      // tool type 4: draw a filled rectangle
      if (toolType == 4)
      {
         page.setColor(currentColour);
         page.fillRect(x[0], y[0], (x[1] - x[0]), (y[1] - y[0]));
      }

      // tool type 5: draw a filled oval
      if (toolType == 5)
      {
         page.setColor(currentColour);
         page.fillOval(x[0], y[0], (x[1] - x[0]), (y[1] - y[0]));
      }

      // tool type 6: draw the line
      if (toolType == 6)
      {
         page.setColor(currentColour);
         page.drawLine(oldX, oldY, newX, newY);
      }
   }

   // unused methods from listener interfaces
   public void mouseEntered(MouseEvent e) {}
   public void mouseExited(MouseEvent e) {}
   public void mouseMoved(MouseEvent e) {}
   public void mouseClicked(MouseEvent e) {}   
}

Answer 1

您好像在引用Paintbrush包中的paint类，但Paintbrush类本身声明package PaintBrush。您没有告诉您如何告诉NetBeans运行哪个applet。但是请尝试将包语句更改为package paint，看看是否有效。